Precision substrate storage container and retaining member therefor

ABSTRACT

The presser member ( 1 ) of the present invention is shaped from different materials for the contacting part ( 5 ) to press-hold the precision substrates ( 15 ) and for the parts excepting the said contacting part ( 5 ). The presser member ( 1 ) is shaped from a thermoplastic elastomer for a rectangular frame part, a contacting part ( 5 ) formed in a pair of structuring parts ( 4 ) provided in such a fashion as to inwardly extend from each of a pair of oppositely facing two sides and a second contacting part ( 11 ) formed in the extension peripheral part extending via a supporting part ( 10 ), the other parts being shaped from a thermoplastic resin. The aforementioned contacting part ( 5 ) is provided with grooves of a V-formed cross section with inclinations changed in the middle way for receiving the peripheries of precision substrates ( 15 ) and V-grooves for press-holding the peripheries of precision substrates are provided in the resilient pieces ( 12 ) separated and protruded in a comb teeth-like fashion to form the second contacting part ( 11 ).

TECHNOLOGICAL FIELD

[0001] The present invention relates to a precision substrate-containervessel used for containing, storage, stock-keeping, transportation,in-process transfer and so on of precision substrates such as siliconwafers, glass plates for photomasks and the like as well as to a pressermember therein for the precision substrates.

BACKGROUND TECHNOLOGY

[0002] Contamination with minute particles must be strictly avoided inprecision substrates such as silicon wafers, glass plates for photomasksand the like. It is an essential requirement in transportation orstock-keeping of these precision substrates that the works therefor areundertaken in an extremely clean environment so that the substratematerials are handled by an automatized machine in order to avoid dustoccurrence and contamination from the workers' bodies and clothes.

[0003] Even as contained in a precision substrate-container vessel(referred to as a container vessel hereinbelow), it is a possible casethat precision substrates become contaminated by rubbing due tocontacting with the inner walls of the container vessel and by a traceof gaseous emission from the resin forming the container vessel.

[0004] It is therefore essential in the selection of the material of thecontainer vessel to select a material which ensures least contaminationof the precision substrates and, in particular, selection of thematerial of the presser members coming into direct contact with theprecision substrates is an important key requisite.

[0005] As a material constituting the presser members, for example, aproposal is made of a material as described in the official publicationof Japanese Patent Kokai No. 11-163115 which is subjected to a treatmentfor reducing generation and emission of contaminant gases.

[0006] Since contamination with minute particles must be strictlyavoided in precision substrates, as is mentioned before, it is desiredthat the outer environment for using and stock-keeping of the containervessel and the environment inside the container vessel are kept in acondition as clean as possible.

[0007] Along with the recent trend in the semiconductor industriestoward larger and larger diameters of the precision substrates and ahigher and higher densities and higher and higher degrees of integrationin semiconductor devices, furthermore, the inner and outer environmentsof the container vessel are required to be kept in a condition of stillhigher cleanness.

[0008] In compliance with the trend in the precision substrates towardlarger sizes or larger diameters, on the other hand, container vesselsof a large capacity have now come under use with a consequent increasein the surface area and thickness of the presser members resulting in anincrease in the volume of emitted gases responsible for contamination ofthe precision substrates so that it is now required to decrease theabsolute amount thereof.

[0009] Generally stating, thermoplastic elastomer materials forming thepresser members contain low molecular weight constituents and additivesin a relatively high content, as compared with resinous materials, sothat greater volumes of gaseous emission were taken as a matter ofconsequence.

[0010] By virtue of the progress of analytical methods in recent years,it has now become possible to accomplish a good accuracy in conductinganalysis of the kind and amount of emitted gases from a molded articleby a method (the so-called head-space method) for qualitative as well asquantitative analyses, in which the objective material as sealed in ahermetically sealable vessel is heated at a specified temperature or,for example, at 60° C. for a specified length of time or, for example,for 1 hour followed by collection of the gas in the hermeticallysealable vessel to be subjected to gas chromatography, mass spectrometryand others.

[0011] As a result, it has now become clear that the amount of gaseousemission from a polyolefin-based or polyester-based thermoplasticelastomer is greater by about 10 times to 50 times than from athermoplastic resin such as polypropylenes, polycarbonate, polybutyleneterephthalates and the like as a conventional material for formingcontainer vessels and further that thermal decomposition of thesematerials causes generation of a volatile matter such as tetrahydrofuranwhich, once deposited on a precision substrate, cannot be removedcompletely without difficulties.

[0012] Accordingly, it has now become an important problem to take acountermeasure against gaseous emission from a presser member formedfrom a thermoplastic elastomeric material which is liable to a largeamount of emission of gases to be a contamination source.

[0013] Besides, a presser member formed from a thermoplastic elastomeralone has a defect that the amount of creeping deformation is so largethat the holding power is decreased in the course of long-term storageand cannot be re-used necessitating replacement with a fresh memberbecause changes are caused in the pressing position and holding power onthe precision substrates between a member even after a single time ofuse and a fresh member resulting in the lack of reproducibility in theholding conditions of the substrates.

[0014] The present invention, which has been completed in considerationof the above described problems, provides, in containing precisionsubstrates in a container vessel, a container vessel capable ofcontaining precision substrates smoothly and in an optimum press-holdingcondition to be suitable for reducing the amount of gaseous emissionfrom the presser members, which exhibits adverse influences whenprecision substrates are contained in the container vessel as well as apresser member therefor.

DISCLOSURE OF INVENTION

[0015] In order to solve the aforementioned problems, in the presentinvention, in conducting shaping of a presser member of a containervessel for precision substrates, the contacting part for press-holdingthe precision substrates and the parts other than the contacting partare formed from different materials.

[0016] The presser member has a rectangular frame body part shaped insuch a form as to be attachable to the inner side surface of thecovering body and a pair of structuring parts provided in such a fashionas to extend inwardly from each of a pair of two opposite sides of thisframe body part, a contacting part is formed for press-holding theprecision substrates in each of the structuring parts and a groovehaving a V-formed cross section to receive the periphery of a precisionsubstrate is formed in this contacting part. This groove of V-formedcross section has first inclined surfaces at the deeper side and secondinclined surfaces wide-opening toward the open side from the firstinclined surfaces.

[0017] The contacting part of the aforementioned presser member isformed from a thermoplastic elastomer.

[0018] Further, the container vessel for precision substrates accordingto the present invention is provided with presser members, of which thecontacting part with the precision substrates is formed from athermoplastic elastomer and other parts than the aforementionedcontacting part are formed from a thermoplastic resin, mounted thereon.

[0019] It is possible with the presser member according to the presentinvention to greatly decrease the amount of emitted gases as generatedfrom the presser members, which may have an adverse influence whenprecision substrates are contained in the container vessel and alsopossible to hold the precision substrates contained in the containervessel with reliability in an optimum press-holding condition so thatthe precision substrates can be efficiently protected from vibrations,shocks and the like added to the container vessel.

BRIEF DESCRIPTION OF THE DRAWING

[0020]FIG. 1 is a plan view showing a presser member for pressing andholding precision substrates as attached to the inner side surface ofthe covering body and FIG. 2 is an enlarged cross sectional view as curand viewed along the line I-I in FIG. 1 showing the contacting part withprecision substrates provided in the presser member.

[0021]FIG. 3 is a partial enlarged plan view of the part A encircled bythe circle in FIG. 1 and FIG. 4 is an enlarged cross sectional view ascut and viewed along the line II-II in FIG. 3.

[0022]FIG. 5 is a perspective view of the container vessel withattachment of the presser member of the present invention and FIG. 6 isa schematic cross sectional view showing the non-contacting part of thepresser member according to the present invention as inserted into ametal mold.

[0023]FIG. 7 is a schematic cross sectional view of the contacting partof the presser member according to the present invention under formationin a metal mold.

BEST MODE FOR PRACTICING THE INVENTION

[0024] An embodiment of the present invention is described in detail bymaking reference to the accompanying drawing but the present inventionis never limited to the embodiment below.

[0025] Firstly, an example of the container vessel having a pressermember of the present invention attached thereto is described by makingreference to the perspective view illustrated in FIG. 5.

[0026] The container vessel illustrated in FIG. 5 consists of the vesselbody 30 for containing precision substrates and the covering body 31 andeach of the oppositely facing inner wall surfaces in the vessel body 30is provided with supporting parts 32 having a square U-cross section atregular intervals to receive and hold the peripheries of precisionsubstrates in such a fashion as to align and contain precisionsubstrates in a horizontal disposition.

[0027] At least one pair of covering body-engagement parts 33 are formedon the peripheries around the opening part of the vessel body 30 foreffecting engagement of the covering body 31 to the vessel body 30 whileautomatization-compliable grips for automatic transportation or gripparts 34 for manual transportation are attached, according to need, tothe outer wall surface of the vessel body 30.

[0028] A pair of engagement means 35 having an engagement part to becomeengaged with the covering body-engagement part 33 of the aforementionedvessel body 30 are pivotally supported on the side walls of the coveringbody 31 and a protrusion 36 is formed in the part facing the steppedpart formed in the inner periphery of the vessel body 30, when thecovering body 31 is engaged to the vessel body 30, to just fit to thisstepped part. A sealing member of an endless form 37 is mounted tosurround this protrusion in order to maintain hermetical sealability ofthe container vessel.

[0029] A presser member 38 for press-holding precision substrates bycoming into contact therewith is attached to the inner surface of thecovering body 31 and a receiving grooves are formed in this pressermember for fixing and holding the precision substrates in correctpositions.

[0030] The vessel body 30 and the covering body 31 are formed from athermoplastic resin having good moldability and excellent mechanicalproperties as well as little liability to contamination such aspolycarbonates, polybutylene terephthalates, polyether sulfones,polypropylenes and the like and, in particular, thermoplastic resinshaving good transparency such as polycarbonates, norbornene-basedresins, acrylic resins and the like having good transparency are usedwhen see-through visibility of inside of the container vessel isrequired. It is also optional according to need to use an antistaticresin composition by admixture of the aforementioned resins withadditives such as antistatic agents, electroconductive materials and thelike in order to impart antistatic function or electroconductivity.

[0031] As is shown in FIG. 1 and FIG. 2, the presser member 1 of thepresent invention is provided with a rectangular frame part 2 and a pairof opposite structuring parts 4,4 inwardly extending from each of a pairof opposite two sides 3,3 of this frame part 2. These structuring parts4,4 are formed in the form of a truncated triangular column cut in theupper part by an inclined plane and contacting parts 5,5 forpress-holding precision substrates are formed on the upper surfacethereof while grooves 6,6 of a V-formed cross section for receiving theperipheries of precision substrates are formed on the inclined uppersurface of these contacting parts 5,5. Although the side walls of thisV-formed groove 6 can be a combination of simple inclined surfaces, theycan optionally be formed in such a fashion as to have first inclinedsurfaces 7 at the deeper side of the groove and second inclined surfaces8 broadly opening toward the opening side making a larger angle than thefirst inclined surfaces 7.

[0032] The first inclined surfaces 7 of the V-formed groove 6 shown inFIG. 4 are shaped in such a fashion that the angle made with thehorizontal surface of the precision substrate supported within thecontainer vessel is a surface inclined by 1° to 5° so that a precisionsubstrate 15 is held by being pinched between the side walls at thedeeper part of the groove with insertion at the peripheral part into thedeeper part of the V-formed groove 6. Similarly, the second inclinedsurfaces 8 are shaped in such a fashion that the angle made with thehorizontal plane of a precision substrate held within the containervessel is an angle of inclination of 6° to 70° to play a role as a guidefor smoothly guiding the precision substrate toward the deeper part ofthe V-formed groove 6.

[0033] As is shown in FIG. 3, the second inclined surfaces 8 are shapedwith alternate extension of the inclined surfaces with asymmetry in theup to down direction and are shaped to facilitate smooth and reliableguiding of the peripheral part of the precision substrate 15 toward thedeeper part of the V-formed groove 6.

[0034] With a V-formed groove 6 having a cross sectional profileforwardly narrowing in two steps broadened from the first inclinedsurfaces 7 to the second inclined surfaces 8, when a covering body 2having the presser member and attached to the vessel body is beingclosed, the second inclined surfaces 8 come into contact with theperiphery of the precision substrate 15 contained inside and then theperiphery of the precision substrate 15 slides as such on this secondinclined surface to enter between the first inclined surfaces 7 to beguided smoothly towards the deeper part of the V-formed groove 6 withreliability so that the mirror-polished surface of the precisionsubstrate is safe from contacting with the side walls of the groove byvirtue of the side walls of the groove making inclined surfaces.

[0035] Having a width of the V-formed grooves 6 approximately equal tothe thickness of the precision substrate 15, the precision substrate 15can be held with reliability within the V-formed groove 6 so thatgeneration of particles caused by rubbing and the like due to vibrationsand revolutions encountered during transportation of the containervessel can be prevented. Further, the precision substrate 15 can be heldreliably without falling out of the V-formed groove 6 even when shockssuch as dropping and the like are added to the container vessel so thatbreaking of the precision substrates can be prevented.

[0036] In order to enable holding of each of the precision substrates ina resilient contacting condition, each contacting part 5 of the pressermember is provided with slits 16 formed between adjacent contactingparts so as to allow independent contacting of each contacting part withthe precision substrate.

[0037] In order to have the precision substrates prevented from wearingand breaking by the revolution due to vibrations during transportationof the container vessel, it is preferable to set the contacting part 5in such a fashion that the interior angles made by the lines connectingthe respective positions at both of the right and left sides coming intocontact with the precision substrate and the center point of theprecision substrate is in the range from 60° to 150° or, preferably,from 90° to 120°.

[0038] At the inward side of a pair of the structuring parts 4,4provided in such a fashion as to be inwardly extended from each of apair of oppositely facing two sides 3,3 of the aforementioned frame bodypart 2, prop parts 10,10 are integrally provided to be connected to theother pair of oppositely facing two sides 9,9 of the frame body part 2while second contacting parts 11,11 coming into contact with theperipheries of the precision substrates are formed on the extensionperipheries extending from each side of these prop parts 10,10.

[0039] These second contacting parts 11,11 are shaped in the form of amultiplicity of resilient pieces 12 divided and protruded like combteeth and the end point of this resilient piece 12 is provided with agroove 13 which receives the periphery of the precision substratecontained in the container body to be held in engagement.

[0040] The side walls of this V-groove 13 can be a combination of simpleinclined surfaces but it is optional to shape each of them in such afashion, like in the V-formed groove 6 of the contacting part shown inFIG. 4, as to have a dually inclined surface broadening with a largerangle at the opening side than at the deeper side.

[0041] It is optional that the V-formed groove 6 and the V-groove 13each have the same cross sectional profile as the V-formed groove 6shown in FIG. 4 or, alternatively, either one alone has the same crosssectional profile as shown in FIG. 4.

[0042] The resilient piece 12 formed in the second contacting part 11exhibits resilience and plays an important role to accomplish safertransportation by protecting the precision substrates from strongimpacts added when the container vessel is dropped or so.

[0043] While it is preferable that, as is shown in FIG. 1, the secondcontacting parts 11 are provided in such a fashion as to face oppositelyin the up to down direction at a regular pitch, it is optional toprovide the same in an alternate arrangement as a whole by providingeither one alone of the oppositely facing two rows with a secondcontacting part (in every two stages for one side). The contactingcondition with the precision substrate in this case is three-pointcontacting.

[0044] An engagement means 14 consisting of a plurality of notches orprotrusions is provided on the peripheral part of the frame body 2 andthey come into engagement with the engagement means formed on the innerside surface of the covering body enabling free mounting and demountingof the presser member 1 onto and from the inner side surface of thecovering body.

[0045] In the presser member 1 of the present invention, it ispreferable that the above-mentioned contacting part 5 and the secondcontacting part 11 inter alia are shaped from a molding materialdifferent from that of other parts of the presser member 1 than theaforementioned contacting parts 5,11 (referred to as the non-contactingparts hereinafter) and further they are formed integrally.

[0046] It should be understood here that the contacting parts formedfrom a thermoplastic elastomer are not limited to the V-formed groove 6and the V-groove 13 actually coming into contact with the precisionsubstrates but include the resilient parts divided like leaf springs soas to come into resilient contact with every one of the precisionsubstrates facing the presser member.

[0047] In consideration of absorption and mitigation of shocks added tothe precision substrates when the container vessel containing themreceives a shock, it is preferable that the aforementioned contactingparts 5,11 are shaped from a polyester-based thermoplastic elastomer ora polyolefin-based thermoplastic elastomer having a good flexuralresilient strength.

[0048] In contrast thereto, it is preferable that the non-contactingparts of the presser member are formed from a material having a highmodulus of rigidity and still having good miscibility with theaforementioned molding material of the contacting parts 5,11.

[0049] For example, when a polyester-based thermoplastic elastomer isselected for the contacting parts of the presser member, polyethyleneterephthalates, polybutylene terephthalates and polycarbonates as wellas resin alloys thereof are satisfactory for the non-contacting partsand, when a polyolefin-based thermoplastic elastomer is selected for thecontacting parts 5,11 of the presser member, it is preferable to selecta polypropylene or polyethylene for the non-contacting parts.

[0050] Nextly, a method for the preparation of the presser member of thepresent invention consisting of different molding materials is describedby making reference to the schematic drawings of the resin-molding metalmolds shown in FIG. 6 and FIG. 7.

[0051] In these figures, the molding metal mold consists of a fixedmetal mold 20 and a movable metal mold 21.

[0052] The non-contacting part 22 forming a part of the frame body partand the structuring part of the presser member is shaped in advance froma polycarbonate, polybutylene terephthalate or a resin alloy of apolycarbonate and a polybutylene terephthalate by using a metal mold forexclusive use.

[0053]FIG. 6 shows the non-contacting part 22 of a presser member shapedin advance as inserted into the cavity 23 of a metal mold for molding ofthe contacting part.

[0054]FIG. 7 shows a metal mold with insertion of the non-contactingpart 22 of the presser member as in FIG. 6 and as mounted on aninjection molding machine (not shown in the figure) followed by moldfastening and filling of the cavity 23 for shaping of the contactingpart with a resin melt which is different from that for thenon-contacting part 22 from the injection port 24.

[0055] While the metal mold shown in FIG. 6 and FIG. 7 is of thethree-plate structure, it is not limited thereto but optionally can bethat of the two-plate structure by using a hot runner. It is alsooptional that the contacting part is first molded and then followed bysubsequent molding of the non-contacting part 22 to be integratedtherewith.

[0056] While a method is described above in which either of thenon-contacting part 22 and the contacting part is molded in advance tobe integrated with the other part molded subsequently, it is optional,differently therefrom, to successively mold different molding materialswith a single metal mold by using a two-color molding machine.

[0057] In this case, the metal mold is filled with the molding materialfor either one of the parts followed by formation of another cavity forthe other part by sliding or rotating the core of the metal mold, whichis filled with a different resin to be integrated with the previouslymolded part.

[0058] The presser member 1 of the present invention is attached to thecovering body by fitting the engagement means 14 of the frame body partof the presser member 1 shown in FIG. 1 to the engagement means formedon the inner side surface of the covering body 31 shown in FIG. 1. Inorder to avoid occurrence of frictional sliding there between the twoparts of a thermoplastic resin, it is preferable that this part also ismolded from the same thermoplastic elastomer as the contacting part andintegrated with the frame body part.

[0059] In the presser member of the present invention, while the partscoming into contact with and the parts not coming into contact with theprecision substrates are shaped from different molding materials, thenon-contacting parts 22 are shaped from a thermoplastic resin and onlythe contacting part 5 and the second contacting part 11 coming intocontact with the precision substrates as well as the parts therearoundare shaped from a thermoplastic elastomer so that, as compared withconventional presser members, the amount of use of the thermoplasticelastomer can be decreased to 1/3 to 1/6 in the volume ratio.Accordingly, the amount of gaseous emission generated during storage ofprecision substrates in the container vessel can also be greatlydecreased approximately in proportion thereto so that, even in a case oflong-term storage of precision substrates within the container vessel,it can be used without contamination and without a disadvantage ofquality degradation.

[0060] Since the non-contacting part occupying most of the pressermember can be shaped from a thermoplastic resin of high rigidity, theamount of creeping deformation can be reduced by far as compared withconventional presser members shaped from a thermoplastic elastomer aloneto enable long-term storage and re-use of the container vessels.

[0061] By means of the V-formed grooves having inclined surfaces ofdifferent angles provided in the contacting part of the presser member,furthermore, it is possible in closing the vessel body containingprecision substrates by bringing the covering body into engagement, tosmoothly and reliably conduct the precision substrates inside of thecontainer vessel into the V-formed grooves and the V-grooves provided inthe second contacting part and it is possible that, after closure of thecovering body, the precision substrates conducted into theaforementioned grooves can be held reliably within the grooves and anoptimum press-holding condition can be accomplished of the precisionsubstrates contained therein because the resilient pieces of the secondcontacting part serve to press-hold the precision substrates withresilience.

[0062] Although the above-given description of the practicing mode isdescribed for a front retainer attached to the inner side surface of thecovering body, the present invention is not limited thereto but the sameis applicable also to the rear retainer attached to the side walloppositely facing the opening of the container vessel in such a fashionas to face the aforementioned front retainer to shape the contactingpart with the precision substrates from a thermoplastic elastomer and toshape the other parts from a thermoplastic resin different therefrom tobe integrated.

1. A presser member in a container vessel for precision substrates whichis a presser member for precision substrates attached to a containervessel for precision substrates consisting of a container vessel bodyfor precision substrate having an opening at one end to containprecision substrates and a covering body engageable with theaforementioned container vessel body and is characterized in that theaforementioned presser member is shaped from different materials for acontacting part to press-hold the precision substrates and the partsexcepting the contacting part:
 2. The presser member in a containervessel for precision substrates described in claim 1 in which theaforementioned presser member is shaped in such a fashion as to beattachable to the inner side surface of the aforementioned covering bodyand has a rectangular frame body part and a pair of structuring partsprovided in such a fashion as to inwardly extend from each of a pair ofoppositely facing two sides of the frame body part, a contacting partbeing formed in each of the structuring parts for press-holdingprecision substrates and the contacting part being provided with grooveshaving a V-formed cross section to receive the peripheral parts of theprecision substrates.
 3. The presser member in a container vessel forprecision substrates described in claim 2 in which the aforementionedpresser member has a second contacting part consisting of a plurality ofresilient pieces separated and protruded in a comb teeth-like fashion.4. The presser member in a container vessel for precision substratesdescribed in claim 2 in which the side walls of the groove having aV-formed cross section provided in the aforementioned presser memberhave first inclined surfaces in the deeper side of the groove and secondinclined surfaces widening in a large angle at the opening side from thefirst inclined surfaces.
 5. The presser member in a container vessel forprecision substrates described in claim 1 in which the contacting partof the aforementioned presser member is shaped from a thermoplasticelastomer and the parts excepting the contacting part are shaped from athermoplastic resin.
 6. The presser member in a container vessel forprecision substrates described in claim 2 in which the contacting partof the aforementioned presser member is shaped from a thermoplasticelastomer and the parts excepting the contacting part are shaped from athermoplastic resin.
 7. The presser member in a container vessel forprecision substrates described in claim 1 in which the contacting partof the aforementioned presser member is shaped from a polyester-basedthermoplastic elastomer and the parts excepting the contacting part areshaped from a polycarbonate resin.
 8. The presser member in a containervessel for precision substrates described in claim 2 in which thecontacting part of the aforementioned presser member is shaped from apolyester-based thermoplastic elastomer and the parts excepting thecontacting part are shaped from a polycarbonate resin.
 9. A containervessel for precision substrates characterized in that a presser member,of which a contacting part coming into contact with the precisionsubstrates is shaped from a thermoplastic elastomer and the partsexcepting the aforementioned contacting part are shaped from athermoplastic resin, is attached thereto.